Peel the onion and core the peppers and cut into 3cm squares. Place these into the slow cooker along with the minced garlic.
Add the ginger, cornflour and chilli and stir well to coat the vegetables.
Add the sugar, soy sauce, vinegar, tomato ketchup, pineapple chunks and juice from the can and then top up with the apple juice. Mix everything together.
Cook on low for 4-5 hours, stirring half way through cooking.
Make the batter
In a large mixing bowl beat the egg and water together. Then gradually sieve in the plain flour, corn flour and baking powder while whisking continuously to avoid any lumps.
Once the flour is mixed in, stir in 1 tsp of salt and a pinch of black pepper. Set the batter aside whilst the chicken is prepared.
Prepare the chicken
Remove any sinew from the chicken and cut each breast into chunks of 3-4cm square (approximately 6-8 chunks per chicken breast depending on their size).
In a bowl add garlic powder, 1 tsp of the salt and a pinch of black pepper and mix. Now put the chicken pieces in the bowl and coat evenly with the seasoning.
In a separate bowl put in 2 tablespoons of flour, take each piece of seasoned chicken and dredge in the flour making sure all sides are covered. The flour helps the batter to stick to the chicken.
Cook the chicken
Place a large frying pan over a medium to high heat then pour in the oil to a depth of around 1 to 2 cm (depending on the size of the pan not all of the 400ml of oil may be required). After 1 - 2 minutes test the oil is hot enough to begin cooking by dropping in a little of the batter (see recipe notes).
Now dip each piece of the chicken in the batter ensuring each piece is submerged entirely - I find it easiest to do this using cooking tongs. Transfer the pieces to the frying pan carefully placing them into the oil as to avoid any of the hot oil splashing. Leave space between them so they don't stick together whilst cooking. Fry for around 3-4 minutes on each side.
Test the chicken is cooked through by taking one of the fattest pieces and cutting in half, the chicken should be white with clear juices. The batter should be crisp and golden.
Place the cooked chicken pieces on a wire rack over a tray for a few minutes to allow any oil to drip away. The chicken pieces can be placed into the sauce in the slow cooker for the final 30 minute of cooking (to entirely soak them in the sauce!). Otherwise enjoy them crisp and pour the sauce over when serving.
To test the oil is hot enough to begin frying the chicken pieces, drop a small amount of the batter into the oil. If the batter forms a ball with small bubbles around it and begins to float and turn golden, you're good to go with frying the chicken!
Checking Chicken is Cooked
To test that the chicken pieces are cooked through, remove a larger piece from the oil. Cut into the middle with a sharp knife and the chicken inside should be white throughout and have clear juices, the batter should be crisp and golden.
Frying In Batches
Depending on the size of the frying pan used, the chicken pieces may have to be fried in batches. The size of the pan will also determine how much oil is required.